1. Field of the Invention
Generally, the invention relates to a pushbutton tuner. In particular, the invention relates to such tuners that do not have a conventional treadle bar and in which the overall height of the tuner is minimized by placing key components such as the pushbutton assemblies, carriage drive means and crown gear horizontally in the tuner frame for horizontal movement therein.
2. Prior Art
Conventional pushbutton tuners have treadle bars which are used to translate pushbutton actuation or operation of the manual tuning control into movement of the core carriage for positioning the cores within a coil housing for tuning the radio. The method by which such conventional tuners operate normally includes the following steps: manually tuning the radio to position the treadle bar and core carriage at a location representative of a predetermined frequency, pulling out one of the pushbuttons to thereby free a memory cam, pushing in the pushbutton and the memory cam to position the memory cam against the treadle bar, further pushing in the pushbutton without moving the treadle bar or cam to lock the cam and then releasing the pushbutton. Having thereby set the predetermined frequency on the memory cam, that frequency can always be recalled by simply pushing in the pushbutton to reposition the treadle bar and core carriage.
The problem is that rotatably mounted treadle bars require too much vertical height for effective operation and have thereby been a limiting factor in reducing the overall vertical height of the tuner. The same is true of the crown gear which is a wide gear, due to the gear reduction required, and is normally vertically disposed in the tuner for rotation about a horizontal axis.
Thick tuners have become objectionable to radio manufacturers, particularly automobile radio manufactures. For example, the excessive materials required in construction have run the cost up too high; the available space for a radio in an automobile dashboard has been continuously reduced; the introduction of FM with AM components in the radio and the combining of the radio with tape decks has increased the overall thickness of the entertainment center package.
Further, innovations in semiconductor technology have made possible the fully electronic tuning of a radio in a relatively compact package. However, car radio manufacturers still require slug tuned sets in their line of radios and there is a need for such a compact slug tuned set which can occupy the same physical space of a fully electronic set or is adaptable for use with a hybrid radio which is both slug tuned, for AM for example, and electronically tuned, for FM for example.
A flat treadlebarless pushbutton AM/FM tuner has been proposed. One such system is shown in Olah, U.S. Pat. No. 3,727,156, assigned to the same assignee as is the present invention, using horizontal slides in the pushbutton assemblies to activate the core carriage through a complex rack and gear arrangement for positioning the cores in the core housing. The proposed radio also shows declutch and declutch disabling means. While the overall height of the proposed tuner is minimized, measuring 3/4 of an inch to 1 inch in overall vertical height, it is not thin enough. The present need is for a radio-tape player combination, for example, that is no more than 26 mm. high. Thus, thinness and simplicity continue to be a nagging problem for tuner manufacturers.
Applicant has overcome the problem in the present invention through the use of a horizontal slide bar to drive the tuning means and by orienting all key components, such as the pushbutton slide mechanisms and the crown gear horizontally. While a similar horizontal slide with V shaped grooves has been known previously, one such slide being shown in Wolf, U.S. Pat. No. 3,247,728, assigned to the same assignee as is the present invention, there the slide is used in a conventional AM/FM tuner with a treadlebar to selectively actuate an AM/FM selector switch between one of two positions.
Through applicant's substitution of a unique horizontal slide bar mechanism for the conventional treadlebar, and by placing the crown gear horizontally, applicant has been able to also obtain significant simplification and improvements in the presettable memory cam apparatus, declutching apparatus and declutching disable apparatus.